Interactive television systems provide viewers with network access to video servers that offer a large plurality of viewing selections. To make a viewing selection, a viewer looks at a menu transmitted by the system and selects a viewing asset. The viewer issues a request for the selected asset through a network that connects his or her television to the interactive television system. In response to receiving the viewer's request, the interactive television system uses the network to stream the requested asset from one of the video servers to the viewer's television. The collection of video data objects and related data objects such as posters, descriptions, and preview objects, may together form a complete viewing asset. In an interactive television system, the selection of available viewing assets is preferably large. Furthermore, the viewing assets themselves often include large video data objects. The desire to offer large selections to viewers means that such systems need very substantial data storage resources for viewing assets.
An interactive television system may store a large amount of asset data on an array of servers. Typically, only a subset of the servers is accessible to a single viewer, because one server cannot server every viewer. In such a system, an individual asset may have to reside on several servers so that different viewers can access the asset.
The collection of accessible assets may also change over time. Changes to the collection of assets may respond to asset popularity shifts and/or viewing population changes.